Finite Element Representation of Two-Phase Fluid Flow Through a Naturally Fractured Reservoir

In this paper, the numerical solution of non-Newtonian two-phase fluid-flow through a channel with a cavity was studied. Carreau-Yasuda non-Newtonian model which represents well the dependence of stress on shear rate was used and the effect of n index of the model and the effect of input Reynolds on the attribution of flow were considered. Governing equations were discretized using the finite volume method on staggered grid and the form of allocating flow parameters on staggered grid is based on marker and cell method. The QUICK scheme is employed for the convection terms in the momentum equations, also the convection term is discretized by using the hybrid upwind-central scheme. In order to increase the accuracy of making discrete, second order Van Leer accuracy method was used. For mixed solution of velocity-pressure field SIMPLEC algorithm was used and for pressure correction equation iteratively line-by-line TDMA solution procedure and the strongly implicit procedure was used. As the results show, by increasing Reynolds number, the time of sweeping the non-Newtonian fluid inside the cavity decreases, the velocity of Newtonian fluid increases and the pressure decreases. In the second section, by increasing n index, the velocity increases and the volume fraction of non-Newtonian fluid after cavity increases and by increasing velocity, the pressure decreases. Also changes in the velocity, pressure and volume fraction of fluids inside the channel and cavity are more sensible to changing the Reynolds number instead of changing n index.

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Fabrication of a Microchannel Device With a Three-Dimensional Pore Network Using a Sacrificial Sugar Template

Volume 3: Computational Fluid Dynamics; Micro and Nano Fluid Dynamics ◽

10.1115/fedsm2020-20356 ◽

2020 ◽

Author(s):

Haipeng Zhang ◽

Tomer Palmon ◽

Seunghee Kim ◽

Sangjin Ryu

Keyword(s):

Porous Media ◽

Fluid Flow ◽

Pore Structure ◽

Three Dimensional ◽

Pore Network ◽

Compressed Air ◽

Microfluidic Channels ◽

Two Phase ◽

Flow Through ◽

Phase Fluid

Abstract Porous media compressed air energy storage (PM-CAES) is an emerging technology that stores compressed air in an underground aquifer during the off-peak periods, to mitigate the mismatch between energy supplies and demands. Thus, PM-CAES involves repeated two-phase fluid flow in porous media, and ensuring the success of PM-CAES requires a better understanding of repetitive two-phase fluid flow through porous media. For this purpose, we previously developed microfluidic channels that retain a two-dimensional (2D) pore network. Because it was found that the geometry of the pore structure significantly affects the patterns and occupational efficiencies of a non-wetting fluid during the drainage-imbibition cycles, a more realistic microfluidic model is needed to reflect the three-dimensional (3D) nature of pore structures in the underground geologic formation. In this study, we developed an easy-to-adopt method to fabricate a microfluidic device with a 3D random pore network using a sacrificial sugar template. Instead of using a master mold made in photolithography, a sacrificial mold was made using sugar grains so that the mold could be washed away after PDMS curing. First, we made sugar templates with different levels of compaction load, and found that the thickness of the templates decreased as the compaction load increased, which suggests more packing of sugar grains and thus lower porosity in the template. Second, we fabricated PDMS porous media using the sugar template as a mold, and imaged their pore structure using micro computed tomography (micro-CT). Pores within PDSM samples appeared more tightly packed as the compacting force increased. Last, we fabricated a prototype PDMS channel device with a 3D pore network using a sugar template, and visualized flow through the pore network using colored water. The flow visualization result shows that the water was guided by the random pores and that the resultant flow pattern was three dimensional.

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